This disclosure relates to a touch detection device, in particular, to a touch detection device detecting touch events based on a change of an electrostatic capacitance in response to an external proximity object, a display device with a touch detection function including such a touch detection device, and an electronic unit.
In recent years, a display device capable of inputting information by mounting a contact detection device, which is a so-called touch panel, on a display device such as a liquid crystal display device, or integrating the touch panel and the display device, and displaying various button images and the like on the display device instead of typical mechanical buttons has attracted attention. The display device including such a touch panel does not require input devices such as a keyboard, a mouse, and a keypad, and therefore there is a tendency to expand the use of such a display device to portable information terminals such as mobile phones, in addition to computers.
Some methods are included in the touch detection methods, and one of them is an electrostatic capacitance method. For example, Japanese Unexamined Patent Application Publication No. 2008-129708 discloses a touch panel including a plurality of X-direction electrodes and a plurality of Y-direction electrodes arranged to face the X-direction electrodes, and detecting touch events by using a change of an electrostatic capacitance formed in the intersections of the X-direction electrodes and the Y-direction electrodes in response to an external proximity object. These electrodes are formed of a translucent material, however, light transmittance is different between a portion with the electrode and a portion without the electrode, and therefore, these electrodes are possibly viewed from outside. Accordingly, in the touch panel, dummy electrodes are provided between the X-direction electrodes, or between the Y-direction electrodes to reduce the difference of the light transmittance between the electrode region formed with the X-direction electrodes and the Y-direction electrodes and the inter-electrode region arranged with the dummy electrodes, and therefore the X-direction electrodes and Y-direction electrodes are allowed to be hardly viewed from outside.